JPH0135951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to synthetic leather that closely resembles natural leather in appearance and feel.

Conventionally, synthetic leather is produced by laminating a synthetic resin such as polyurethane resin on one side of a base fabric such as knitted fabric, woven fabric, or non-woven fabric, or by impregnating the entire base fabric with a synthetic resin solution and drying it by heating or wet coagulation. Synthetic leather is known, which is obtained by laminating a synthetic resin on one side of impregnated cloth, but it is difficult to distinguish it from natural leather at first glance because the design is expressed by transferring engraved patterns on paper or rolls. It was done. Furthermore, these synthetic leathers lack drapability and are far from natural leather in terms of texture.

On the other hand, with the aim of improving the surface design of vinyl chloride leather, natural pressed products using high-frequency embossing equipment have been put on the market, but most of them are made of thermoplastic synthetic resin film coated with vinyl chloride homopolymer or copolymer. Since polymers are used, there are problems such as off-odor and clouding of glass due to volatilization of the plasticizers contained, as well as lack of dry-cleanability and poor flexibility required for synthetic leather for clothing. It had its drawbacks.

In view of the above, the present inventors have conducted extensive research in order to obtain a flexible leather substitute that does not contain plasticizers and can easily express a surface design equivalent to that of natural leather.
We have discovered that this objective can be achieved by using a resin layer made of a specific polyurethane resin,
The present invention has now been accomplished.

That is, the flexible synthetic leather with excellent high-frequency embossing properties of the present invention has a base material made of fibers having a melting point or decomposition point of 200°C or higher, a 100% modulus of 1 to 30 kg/cm ² and a softening point of 170°C. A polyurethane resin layer with a residual strain rate of 50% or less at 150℃ above ℃ is laminated, and a polyurethane resin layer with a 100% modulus of 1 to 30 Kg/cm ² and a residual strain rate of 40% or more at 150℃ is laminated on the polyurethane resin layer. A foam layer is laminated on top of the polyurethane foam layer at a softening point of 120 to 250℃.
It is made by laminating polyurethane film layers with a residual strain rate of 40% or more at 150°C.

The fibers having a melting point or decomposition point of 200°C or higher that constitute the base material used in the present invention include synthetic fibers such as polyamide, polyester, vinylon, acrylonitrile, semi-synthetic fibers such as rayon, kyupra, acetate, etc. , wool, cotton,
Knitted fabrics, woven fabrics, non-woven fabrics, impregnated fabrics, etc. made from linen etc. can be used. The substrate must have a melting point or separation point of 200°C or higher. If the melting point or decomposition point of the base material is below 200℃,
The heat generated by high frequency may cause the base material to be melted and compressed before the polyurethane foam layer is melted and compressed, or the base material may be compressed and fixed even without melting, making the texture of the base material extremely hard. The texture of synthetic leather becomes worse after high-frequency processing.

In the present invention, the polyurethane resin that is laminated by direct coating or impregnation on the fiber base material is 100%
The % modulus must be adjusted to be between 1 and 30 Kg/ ^cm2 . 100% modulus is 1Kg/cm ²
If it is less than 30 kg/cm 2 , the texture will be very flexible, but the strength will be too weak to be practical as a synthetic leather, and if it exceeds 30 kg/cm ² , the texture will be too hard, which is not preferred. The polyurethane resin layer that is directly coated or impregnated onto the fiber base material must have a residual strain rate of 50% or less at 150°C, particularly preferably 40% or less.
If it exceeds 50%, it is undesirable because it is compressed and fixed by high-frequency embossing and tends to have a hard texture.

Additionally, this polyurethane resin must have a softening point of 170°C or higher. If it is below 170°C, it is not preferable because it softens and melts due to the heat generated by the high-frequency embossing process, penetrates into the fiber base material, and fixes the fibers, resulting in a hard texture. 100% modulus like this, 150℃
Any polyurethane resin, whether polyester or polyether, can be used as long as it satisfies the residual strain rate and softening point conditions.

An example of a preferable wet method is a polyurethane resin that can be used in the wet method in the polyurethane foam layer described below. Furthermore, pigments and dyes for coloring, various other stabilizers, fillers, etc. can be added to the polyurethane resin compounded liquid that is directly applied or impregnated onto the fiber base material.

The polyurethane foam layer is necessary to obtain the excellent high frequency embossing synthetic leather of the present invention. The density of the polyurethane foam layer is preferably 0.1 to 0.8 g/cc. If it is less than 0.1 g/cc, the physical properties will be too weak to be practical, and if it is more than 0.8 g/cc, the texture will not only become hard, but there will be no point in providing a foam layer, which is not preferable.

The thickness of the polyurethane foam layer is related to the desired use and texture of the synthetic leather, but in general, if it exceeds 2000μ, the synthetic leather will become thick and lumpy, and wrinkles will increase after high-frequency embossing. , which is not preferable because the texture becomes hard. The 100% modulus of the polyurethane foam layer must be adjusted to 1-30 Kg/ ^cm2 . If it is less than 1 Kg/cm ² , the physical properties are too weak to be practical, and if it is 30 Kg/cm ² or more, the texture becomes hard. Residual strain rate is 150℃
Desirably 40% or more. If it is less than 40%, the proportion compressed and fixed by high-frequency embossing will be small, making the design unclear and undesirable.

The polyurethane film layer must be made of polyurethane that has excellent heat resistance and high frequency embossing properties.
Such polyurethane must be a polyether-based or polyester-based urethane resin with a softening point of 120°C or higher, preferably 160°C or higher. If the softening point is below 120℃, the film layer will be heated above the softening point during high-frequency embossing, which will not only cause the film layer to adhere to the mold or break the film layer, but also cause thermal deterioration of the polyurethane film layer. Therefore, it is unfavorable in terms of appearance and physical properties. The residual strain rate of the polyurethane film layer is 40 at 150℃
% or more, preferably 50% or more. If it is less than 40%, it is not preferable because a design cannot be clearly imparted to the surface of the synthetic leather by high-frequency embossing.

The polyurethane foam layer uses polyether polyurethane or polyester polyurethane,
Formed by dry or wet methods. In the case of the dry method, the polyol component is polyether polyol such as polypropylene glycol, polytetramethylene glycol, or triol, polycarbonate polyester, polyester obtained by reacting a hydroxyl compound with a dibasic acid, or ε-caprolactone polyester. As,
Using a urethane prepolymer obtained by reacting an excessive amount of diisocyanate such as diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. and a catalyst, foaming and curing is performed under heating and humidification, or in an emulsion of a polyurethane polymer. It is formed by heating and drying a so-called mechanical foam, which disperses bubbles by mechanically mixing air into the foam.

On the other hand, in the case of the wet method, polyether polyols such as polypropylene glycol and polytetramethylene glycol, polycarbonate polyesters, ε-caprolactone polyesters, or polyesters obtained by reacting hydroxyl compounds and dibasic acids are used as the polyol component. As,
Using a solvent solution such as dimethyl formamide of a polyether-based polyurethane elastomer or a polyester-based polyurethane elastomer obtained by reacting a diisocyanate such as diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and a low molecular weight chain extender. Solvent removal is performed using a wet method to form a micro-bolus wet foam layer.

Pigments and dyes for coloring, various other stabilizers, fillers, etc. can be added to the polyurethane foam layer. In addition, when providing a polyurethane adhesive between a polyurethane resin layer and a polyurethane foam layer that are directly applied or impregnated onto the fiber base material,
Solvent-type adhesives, emulsion-type adhesives, or water-soluble adhesives made of polyether-based or polyester-based polyurethane resins can be used. A coating method, a spray method, etc. can be carried out as appropriate.

In the synthetic leather of the present invention, in order to make the surface more similar to natural leather, a synthetic resin surface layer can be laminated on the polyurethane film layer to the extent that it does not adversely affect high frequency embossing properties or texture.

This synthetic resin surface layer is formed of a synthetic resin commonly used for the surface layer of synthetic leather, such as polyurethane resin, polyamino resin, polyamino acid resin, polyurethane-modified polyamino acid resin, etc. The synthetic resin surface layer can be prepared by mixing a solvent solution of these synthetic resins with a coloring agent, stabilizer, etc. and applying it directly onto the polyurethane film layer and drying it, or by applying a mixture of a coloring agent, stabilizer, etc. to a solvent solution of the synthetic resin on a release paper. It may also be formed by applying a mixture of agents and transferring this onto the polyurethane film layer.

Release paper can be one coated with silicone or a synthetic resin film (polyethylene film,
A material laminated with polypropylene or the like can be used. The surface of the synthetic resin layer may be printed or surface treated as necessary.

Since the synthetic leather of the present invention is configured as described above, it has excellent high-frequency embossing properties and flexibility, and by high-frequency embossing, synthetic leather that closely resembles natural leather in appearance and feel can be obtained. It is.

Examples of the present invention are listed below, but the present invention is not limited to these Examples.

Example 1 Softening point on flat support with mold releasability
A polyurethane resin solution containing a colorant and a polytetramethylene glycol polyether polyurethane with a residual strain of 90% and a 100% modulus of 30 kg/cm ² at 170°C and 150°C is dried and thickened.
It is coated to a thickness of 20 μm and dried by heating to form a polyurethane film layer, and on the polyurethane film layer, a foamable urethane elastomer containing mainly polypropylene ether glycol and polytetramethylene ether glycol-based isocyanate-terminated polyurethane prepolymers is compounded. The basis weight of the item is 140
g/m ² and heated in a heating machine at a temperature of 115°C for 3 minutes under humidification to foam and harden.
A polyurethane foam layer having a density of 0.48 g/cc, a softening point of 165°C, a 100% modulus of 3 kg/cm ² and a residual strain rate of 100% at 150°C was obtained.

Next, as an adhesive on the polyurethane foam layer.
A polypropylene ether glycol polyurethane resin solution with a 100% modulus of 10 Kg/cm ² and a softening point of 170°C is applied to a dry thickness of 5μ, and after heating and semi-drying, a 100% modulus of 4 kg is applied onto this adhesive layer. /cm ² , a polypropylene ether glycol polyurethane resin layer with a softening point of 220°C and a residual strain rate of 18% at 150°C is formed by wet desolvation on a woven fabric made of 6.6 nylon fibers with a melting point of 250°C. After the processed substrates were bonded together and the adhesive was cured by reaction, the support was peeled off to obtain a laminate. The resulting laminate was placed on a template onto which the pattern of natural leather had been transferred and subjected to high-frequency processing using a high-frequency embossing machine, resulting in a flexible product with an excellent surface design that directly copied the pattern of natural leather. A synthetic leather with a good texture was obtained.

Example 2 A single-sided brushed fabric made of polyester fibers with a melting point of 255°C has a 100% modulus of 3 kg/cm ² on the non-flapped side.
Polypropylene glycol polyurethane resin with a softening point of 210℃ and a residual strain rate of 20% at 150℃.
The thickness is 150μ by applying DMF solution and wet desolvation method.
After forming and drying a polyurethane resin layer, a 100% modulus of 4Kg/cm ² , 150
A DMF solution of polycaprolactone polyester polyurethane resin with a residual strain rate of 80% at °C was applied to a dry thickness of 300μ and a density of 0.25g/cc, and the solvent was removed and dried to form a polyurethane foam layer. A resin solution containing a colorant and a polytetramethylene ether glycol polyurethane resin with a residual strain rate of 80% at 150°C, a softening point of 180°C, and a 100% modulus of 30 kg/cm ² is applied onto the polyurethane foam layer to ensure flat mold release properties. Dry thickness on the support
It was coated to a thickness of 15 μm and heated to a semi-dry state, and immediately a base material on which a polyurethane foam layer was laminated was bonded. After drying by heating, the releasable support was peeled off to obtain a laminate. When the obtained laminate was subjected to high frequency processing under the same conditions as in Example 1, synthetic leather was obtained which had an excellent surface design and a soft feel that closely resembled natural leather.

Example 3 A polypropylene glycol polyurethane resin with a 100% modulus of 3 Kg/cm ² , a softening point of 200°C, and a residual strain rate of 15% at 150°C was applied to the raised side of a one-sided rough brushed blanket made of 6.6 nylon fibers with a melting point of 260°C.
Apply DMF solution and use wet desolvation method to achieve thick texture.
After forming a 200μ polyurethane resin layer and drying, 100% modulus 3Kg/cm ² on the polyurethane resin layer.
Polytetramethylene ether glycol polyurethane resin with residual strain rate of 85% at 150℃
A DMF solution was applied to give a dry thickness of 400 μm and a density of 0.3 g/cc, and after removing the solvent, it was dried to form a polyurethane foam layer. Next, on the polyurethane foam layer, a residual strain rate of 100% at 150°C, a softening point of 210°C,
A resin solution containing a 1.4-butanediol adipate polyester urethane resin with a 100% modulus of 210Kg/cm ² and a coloring agent is applied onto the polyurethane foam layer using a gravure printer to a dry thickness of 5μ, and then heated and dried. The solvent was removed to obtain a laminate. When the obtained laminate was subjected to high frequency processing under the same conditions as in Example 1, synthetic leather was obtained which had an excellent surface design and a soft feel that closely resembled natural leather.

Comparative Example 1 Softening point 220℃, 150℃ on flat releasable support
Residual strain rate at °C is 20%, 100% modulus is
A resin solution prepared by blending a coloring agent with ethylene glycol adipate polyester polyurethane resin having a weight of 70 kg/cm ² is applied to a dry thickness of 21 μm, and this is heated and dried to form a polyurethane film layer. A foamable urethane elastomer compound mainly composed of 1.4-butanediol adipate polyester-based isocyanate-terminated polyurethane prepolymer was applied to the surface at a basis weight of 180 g/m ² , and this was heated for 3 minutes under humidification in a heating machine at a temperature of 120°C. Foamed and hardened, thickness 350μ, density 0.55
g/cc, softening point 180℃, 100% modulus 15Kg/
A polyurethane foam layer with a residual strain rate of 25% at cm ² and 150° C. was obtained. An ethylene glycol, diethylene glycol adipate polyester polyurethane resin solution with a 100% modulus of 20 kg/cm ² and a softening point of 175°C is applied as an adhesive onto the polyurethane foam layer so that the dry thickness is 15 μm, and immediately melted onto the adhesive. 6. Knitted fabrics made of nylon fibers were bonded together at a temperature of 215°C, and after the adhesive was cured by reaction, the support was peeled off to obtain a laminate. Example 1 The obtained laminate
As a result of high-frequency embossing under the same conditions as above, a hard synthetic leather with an indistinct surface design was obtained.

Comparative Example 2 A polyvinyl chloride blend consisting of 100 parts of polyvinyl chloride resin, 70 parts of plasticizer, and 5 parts of pigment was applied to a thickness of 25 μm on a flat mold-releasing support, and this was heated to gel. A polyvinyl chloride film layer with a % modulus of 30 Kg/cm ² , a softening point of 160°C, and a residual strain rate of 100% at 150°C, and on the polyvinyl chloride film layer, 100 parts of polyvinyl chloride resin and 70 parts of plasticizer. ,
A foamable polyvinyl chloride compound consisting of 5 parts of stabilizer, 3 parts of pigment, and ⁵ parts of blowing agent is applied at a basis weight of 200 g/m2, gelled at a temperature of 150°C, and then foamed at 190°C to create a thick texture. 400μ, density 0.5g/cc Softening point 160℃, 100
% modulus 4Kg/cm ² , residual strain rate at 150℃
A 95% polyvinyl chloride foam layer was obtained. 100% modulus as adhesive on the PVC foam layer
A 1.4-butanediol adipate polyester polyurethane resin solution with a weight of 20Kg/cm ² and a softening point of 175℃ was applied to a dry thickness of 15μ, and a knitted fabric made of rayon fiber with a decomposition point of 260℃ was immediately applied as a base material. After combining and curing the adhesive, the releasable support was peeled off to obtain a laminate. The obtained laminate was subjected to high-frequency embossing under the same conditions as in Example 1, and as a result, vinyl chloride leather with a clear surface design but a hard texture was obtained.

Claims (1)

[Claims] 1. A base material made of fibers having a melting point or decomposition point of 200°C or higher and a 100% modulus of 1 to 30.
Kg/cm ² , laminated with polyurethane resin layers with a softening point of 170°C or higher and a residual strain rate of 50% or less at 150°C,
A polyurethane foam layer with a 100% modulus of 1 to 30 kg/cm ² and a residual strain rate of 40% or more at 150°C is laminated on the polyurethane resin layer, and a polyurethane foam layer with a softening point of 120 to 250°C and a softening point of 150°C is laminated on the polyurethane foam layer. A flexible synthetic leather with excellent high-frequency embossing properties, made by laminating polyurethane film layers with a residual strain rate of 40% or more. 2. A flexible synthetic leather with excellent high-frequency embossing properties as claimed in claim 1, wherein a polyurethane resin layer and a polyurethane foam layer are laminated with a polyurethane adhesive layer interposed therebetween.